EP3191012B1 - Dental implant - Google Patents

Description

The present invention relates to a dental implant formed of an anchoring body defined between an apical end and a cervical end, which anchoring body is a body of a first predetermined length and has on its outer surface and along any said first predetermined length at least one thread.

Preferably, the dental implant is made of titanium but an alternative to titanium, for performing the dental implant, is to choose zirconia, an alloy of these two elements, or any other biocompatible material.

A dental implant is conventionally used to make a dental prosthesis, in order to restore a patient, partially or totally edentulous, a chewing function, oral comfort and aesthetics.

To this end, during the installation of the implant, the latter is first fixed by screwing into a previously formed housing in the bone of the jaw, on an implantation site. Then, a prosthetic element, fixed or removable, is placed on the implant via a pillar or a neck: a prosthesis constituted by the prosthetic element mounted on a prosthetic assembly comprising the implant is thus obtained. and the collar or the pillar.

In general, the dental implants known from the state of the art are formed by a threaded anchoring body with an external diameter of between 3 mm and 6 mm, this diameter being chosen so as to allow a distribution of the pressure loads during the placement of the prosthetic element and during chewing.

The document US3466748 discloses a dental implant having an anchoring body comprising a plurality of distinct parts: a first threaded part whose diameter of the turns (forming the thread) is constant over the entire height and a second part whose Diameters of the turns (forming the net) decrease along the dental implant towards its apical end. The anchoring body also has unthreaded portions, the extreme portion of the anchor body in contact with the support of the prosthesis: the coronal part of the dental implant according to this prior document is not threaded. In addition, the dental implant according to this prior document has an unthreaded central portion between the first and the second threaded portion, which is problematic when it comes to removal of the dental implant. Indeed, since the bone tissue reforming bone around the central portion of the dental implant, the latter is truly blocked and can not be unscrewed since the threaded portions are separated by the reformed bone.

The document WO2011 / 085982 also discloses a first dental implant whose coronal portion is not threaded and a second dental implant of which only two distinct parts have threads. More particularly, according to this second dental implant described in this prior document, the two threaded portions are intended to be located in the cortical bone while the central portion of the dental implant located between these two threaded portions is devoid of net. It is therefore a bi-cortical anchorage responsible for lateral deflection creating problems of fixation of the dental implant at the neck of the latter. In fact, since the cortical bone is denser than the cancellous bone, if the apical part of the dental implant is fixed in the apical cortical bone, the flexibility of the implant is reduced and greater pressures are exerted on the implant. cervical cortical bone. Therefore, it is much preferable that the apical portion of the dental implant is staked in the cancellous bone.

Moreover, this type of dental implant such as that described in the document WO2011 / 085982 is less and less used on the one hand because of the problems related to the lateral deflection but also on the other hand, because they can not be removed by simple unscrewing. In effect, as for the dental implant disclosed in the document US3466748 since the bone tissues reform bone around the central portion of the dental implant, the latter is effectively blocked and can not be unscrewed since the threaded portions are separated by the reformed bone.

The document WO2010 / 021478 discloses meanwhile a dental micro-implant (miniature implant) having threads of increasing diameter from the cervical portion to the apical portion: it is therefore at the coronal portion of this dental implant of the state of the art that the diameter of the turns forming the net is the smallest.

Unfortunately, with these implants of the state of the art, the stability of the peri-implant bone is not systematically guaranteed. Indeed, crater-shaped postoperative bone loss often occurs after a certain period of operation, and is accompanied by a loss of attachment of the peri-implant mucosa characterized by the formation of pockets between the gingiva and implants in the body. which is observed penetration of the oral bacterial flora. In addition, as noted above, some of these dental implants can not be unscrewed as soon as they are truly stuck in the bone reforming around the dental implant.

• d'une part, ces pertes peuvent être induites par un manque d'attache de la muqueuse lié par exemple à : (i) un manque de biocompatibilité du col ou du pilier, (ii) des dévissages trop fréquent des piliers, (iii) des techniques prothétiques inadaptées ; et/ou
• d'autre part, ces pertes peuvent être provoquées par une destruction osseuse induite, soit par des contraintes de mastication élevées entraînant des forces de cisaillement excessives à l'interface os/implant, soit par des déformations éventuelles des parois du corps d'implant.

It is suggested that peri-implant bone loss in cervical cortical bone may have different causes:

• on the one hand, these losses can be induced by a lack of attachment of the mucosa linked for example to: (i) a lack of biocompatibility of the neck or the pillar, (ii) excessive unscrewing of the abutments, (iii) unsuitable prosthetic techniques; and or
• on the other hand, these losses can be caused by induced bone destruction, either by high mastication stresses resulting in excessive shear forces at the bone / implant interface, or by possible deformations of the walls of the implant body.

The loss of bone mass in the cervical cortical bone (which is by definition poorly vascularized) defined at the periphery of a cervical end of the implant results in a reduction in mechanical stability (primary stability) and a gradual increase in the amount of leverage extra-osseous, which progressively amplifies the mechanical stresses generated on the residual bone anchorage and thus a possible acceleration of the bone destruction.

In addition to the loss of the mechanical qualities of the implant and therefore the masticatory capacity of the patient, the loss of bone mass may be at the origin of a receding gingiva on the implantation site which has two major consequences. On the one hand, the loss of the gum mass makes visible part of the neck or the pillar of the prosthetic assembly, which decreases the aesthetic quality. On the other hand, the loss of the mass of the gum corresponds to a loss of the natural barrier to the bacteria present in the oral cavity which, when the loss of gum is sufficiently important around the neck or the pillar, can be housed between the implant and the gum, which frequently results in inflammation of the gum.

More dramatically, bacteria can enter and settle in bone mass, resulting in infections or abscess formation in the bone, which is particularly difficult to treat.

There is therefore a need to obtain a dental implant which makes it possible to reduce or even annihilate these post-operative peri-implant bone losses of the cervical cortical bone. There is also a need to provide a dental implant that can be easily unscrewed for example for replacement.

To overcome this need, it is provided according to the present invention an implant as described above, characterized in that said anchoring body has on at least a coronal portion of the implant a portion of said at least one thread of diameter nominal d _n greater than one external diameter d _e of said anchor body on said coronal portion in a first ratio d _n / d _e between 2.00 and 4.00, preferably between 2.00 and 3.00.

In this way, by the ratios between the nominal diameter of the thread and the external diameter of the anchoring body provided according to the invention, an implant is obtained whose mechanical stability is preserved while reducing the pressure exerted in the cortical bone. cervical.

Indeed, in the context of the present invention, it was surprisingly observed that, not only by reducing the diameter of the anchor body and by increasing the diameter of said at least one thread in the first report d _n / d _e between 2.00 and 4.00, the mechanical stability of the implant was not degraded, but on the contrary the mechanical stability of the implant is increased in the long term.

According to the invention, it has moreover been determined that such a ratio must be observed at least in the portion (portion) coronary of the dental implant. By the term "portion or coronal portion of the dental implant" is meant, within the meaning of the present invention, the intraosseous portion (or portion) of the dental implant which extends over a length of 2 to 5 mm, preferably over a length of 3 to 4mm from the cervical end of the dental implant towards the apical end thereof.

According to the invention, it has been shown that a reduction of the induced trauma at the bone / implant interface by the chewing forces is obtained by increasing the nominal diameter (and therefore the width of the turns) of the pitch of screw, which increases the bone / implant contact area, increases the bone / implant keying and compression of the bone while decreasing the shear forces.

It is further observed that a less hollow implant body than the state-of-the-art implants, which house a deep inner housing for accommodating the abutment screw, also allows a reduction in the deformations of the implant walls of the implant. implant under chewing forces.

This goal is achieved by significantly reducing the diameter of the implant body, particularly in the cervical portion and increasing the width of the turns to ensure good anchorage in the cortical hard bone. Moreover, large turns make it possible to create space for a generation of spongy bone that is well vascularized between the turns, to reduce the mass ratio: implant material (for example titanium) / bone, while preserving a high primary stability (or mechanical stability) during implant placement and thus stabilization (or improvement) of anchoring of the implant body over time.

• la surface de contact de l'implant dentaire est augmentée, ce qui permet de mieux répartir les contraintes mécaniques auxquelles est soumis l'implant dentaire ;
• les mises en compression des os dense/dur (os cortical) et spongieux sont augmentées, ce qui stimule une reformation rapide du tissu osseux (et donc de l'os) autour de l'implant dentaire ; et
• une quantité importante d'os vivant peut se reformer autour de l'implant dentaire dès lors que son filet présente des spires de grand diamètre entre lesquelles les tissus osseux peuvent se reformer et se fixer (régénération osseuse entre des spires de grande surface tout le long de l'implant dentaire), ce qui augmente le BIC, c'est-à-dire le Bone to Implant Contact.

In other words, in the context of the present invention, it has been determined that a dental implant according to the invention has three main advantages without diminishing the primary stability of the implant (mechanical stability), that is to say without diminishing the anchoring of the turns of the thread of the dental implant into the peripheral bone:

• the contact surface of the dental implant is increased, which makes it possible to better distribute the mechanical stresses to which the dental implant is subjected;
• the compression of dense / hard bone (cortical bone) and cancellous bone is increased, which stimulates a rapid reformation of the bone tissue (and thus the bone) around the dental implant; and
• a large amount of living bone can reform around the dental implant as soon as its net has large diameter turns between which the bone tissue can reform and settle (bone regeneration between large surface coils all along of the dental implant), which increases the BIC, that is to say the Bone to Implant Contact.

Advantageously, said anchoring body is at least partly substantially cylindrical in shape or has a conical-cylindrical or conical conical shape towards said apical end.

Advantageously, said coronal portion is defined by a lateral wall which has a first buccal face and a second palatal face, which palatal face is in a position offset towards said cervical end relative to that of the buccal surface along a longitudinal axis traversing the anchor body and connecting said first cervical end to said apical end.

Optionally, said anchoring body has, at its apical end, at least one tapping groove constituted by at least one longitudinal recess, preferably formed from the apical end towards the cervical end of the anchoring body.

Other embodiments of the dental implant screw according to the invention are indicated in the appended claims.

• ledit implant selon l'invention; et
• un élément transgingival, destiné à traverser la gencive et agencé pour être relié à la portion coronaire du corps d'ancrage. Cet élément transgingival est en outre destiné à supporter un élément prothétique.

The present invention further relates to a prosthetic assembly comprising:

• said implant according to the invention; and
• a transgingival element, intended to pass through the gingiva and arranged to be connected to the coronal portion of the anchoring body. This transgingival element is further intended to support a prosthetic element.

Preferably, said transgingival element is a neck that protrudes from the cervical implant end and is disposed in the extension of the coronal portion of the anchor body.

Advantageously, the transgingival element is a pillar connected, preferably removably, by means of connection to said coronal portion of the anchoring body.

Other embodiments of the prosthetic assembly according to the invention are indicated in the appended claims.

• La figure 1 illustre un premier mode de réalisation de l'implant selon l'invention.
• La figure 2 illustre un premier mode de réalisation de l'ensemble prothétique selon l'invention.
• La figure 3 illustre un deuxième mode de réalisation de l'ensemble prothétique selon l'invention.
• La figure 4 illustre un troisième mode de réalisation de l'ensemble prothétique selon l'invention.

Other features and advantages of the invention will emerge from the description given below, in a non-limiting manner.

• The figure 1 illustrates a first embodiment of the implant according to the invention.
• The figure 2 illustrates a first embodiment of the prosthetic assembly according to the invention.
• The figure 3 illustrates a second embodiment of the prosthetic assembly according to the invention.
• The figure 4 illustrates a third embodiment of the prosthetic assembly according to the invention.

In the figures, the analogous elements bear the same reference.

The Figures 1a and 1b illustrate a first embodiment of the implant 1 according to the invention.

In these figures, is matched anchor body 2 of the first length L ₁ generally between 10.00 mm and 15.00 mm, forming the implant defined by an apical end _E and a cervical end E _c interconnected by a longitudinal axis to _L.

This longitudinal axis _L, which passes through the anchor body 2 from the apical end _E to the cervical end E _c, corresponds to the axis of rotation of a thread 4 present on an outer surface over the entire length anchor body 2.

The thread 4 is a thread with positive pitch, that is to say which is screwed in a drilling direction D when the screw is rotated along its axis of rotation a _L in the clockwise direction.

The anchoring body 2 has, on at least one coronal portion 3 which extends over a second length L ₂ ranging from 2.00 mm to 5.00 mm, a portion of the thread 4 having a thread (with turns). nominal diameter of _n greater than an external diameter d _e of the anchor body 2 in a first ratio R ₁ = d _n / d _e between 2.00 and 4.00, preferably between 2.00 and 3.90 , advantageously between 2.00 and 3.80, more advantageously between 2.00 and 3.70, alternatively between 2.00 and 3.60, in a particular embodiment, between 2.00 and 3, 50.

Optionally, the first ratio R ₁ = d _n / d _e is between 2.00 and 3.40, preferably between 2.00 and 3.30, more advantageously between 2.00 and 3.20, so that alternatively between 2.00 and 3.10, optionally between 2.00 and 3.00.

Optionally, the first ratio R ₁ = d _n / d _e is between 2.00 and 3.00.

Preferably, the first ratio R ₁ = d _n / d _e is between 2.00 and 2.90, preferably between 2.00 and 2.80, advantageously between 2.00 and 2.70, more advantageously between 2.00 and 2.60, alternatively between 2.00 and 2.50, in a particular embodiment, between 2.00 and 2.40.

Optionally, the first ratio R ₁ = d _n / d _e is between 2.00 and 2.30, preferably between 2.00 and 2.20, more advantageously between 2.00 and 2.10.

The first ratio R ₁ = d _n / d _e is more preferably equal to 2.00 or 2.50.

The first ratio R ₁ = d _n / d _e is even more preferably equal to 3.00 or 3.50.

The first ratio R ₁ = d _n / d _e is even more advantageously equal to 4.00.

The length L ₂ corresponds to the average thickness of the cortical bone of the jaw.

The nominal diameter is the diameter measured between two crest end of the net.

Preferably, the nominal diameter d _n of the thread has a value in a range from 2.50 mm to 6.00 mm, preferably in a range from 4.00 mm to 5.00 mm. The outer diameter d _e of the anchoring body 2 is preferably chosen in a range from 1.20 mm to 3.00 mm.

Preferably, the net, having the ratio R ₁ = d _n / d _e defined above, is present at least over the entire length L ₂ of the coronary portion 3 of implant 1.

Advantageously, the net, having the ratio R ₁ = d _n / d _e defined above, is present over the entire length L ₁ of the implant.

The anchoring body 2 is preferably a solid body made of titanium or zirconia conical in shape converging towards said apical end E _a . In particular, the anchoring body 2 has an apical end outer diameter d _Ea of between 1.50 mm and 2.00 mm and a cervical end outer diameter d _Ec of between 2.50 mm and 3.00 mm. mm.

The net 4 is further characterized by a second ratio R ₂ = n / L ₁ of between 0.50 mm ^-1 and 1.00 mm ^-1 , preferably between 0.60 mm ^-1 and 1.00 mm ^-1. advantageously between 0.70 mm ^-1 and 1.00 mm ^-1 , n representing a predetermined number of peaks 5 of the net 4.

The ratio R ₂ thus represents the peak density per unit length of the implant. For example, for an implant of length L ₁ equal to 10.00 mm, a ratio R ₂ of 0.50 mm ^-1 means that over the length L ₁ is formed a net comprising 5 peaks.

A ratio R ₂ of 1.00 mm ^-1 means that over a length L ₁ equal to 10.00 mm, a net is formed comprising 10 peaks.

Advantageously, the net 4 is further characterized by a third ratio R ₃ = n / L ₂ of between 0.50 mm ^-1 and 1.00 mm ^-1 , preferably between 0.60 mm ^-1 and 1, 00 mm ^-1 , advantageously between 0.70 mm ^-1 and 1.00 mm ^-1 , n representing a predetermined number of peaks 5 of the net 4.

The ratio R ₃ thus represents the density of peaks per unit length L ₂ of the coronal portion 3 of the implant. For example, for a coronal portion 3 of length L ₂ equal to 3.00 mm, a ratio R ₃ of 0.50 mm-1 means that over the length L ₂ , a net comprising 1.5 peaks is formed.

A ratio R ₃ of 1.00 mm ^-1 means that, over a length L ₂ equal to 5.00 mm, a net is formed comprising 5 peaks.

Preferably, the anchoring body 2 has, at its apical end E _, at least one tapping slot 6 constituted by a longitudinal recess formed from the apical end E _a towards the cervical end E _c of the anchoring body. 2.

This second apical portion 8 is typically anchored in the spongy bone portion 4 "of predefined depth 4 'of the jaw.

This second apical portion is further defined by a length L _{2 '} which is a function of the depth 4' of the cancellous bone portion 4 ".

In this context, the length L ₁ = L ₂ + L _{2 '} of the implant is therefore a function, on the one hand, of the depth of the cortical hard bone 3' of the jaw, and on the other hand, of the depth 4 'of the cancellous bone portion 4 "of the jaw.

Preferably, the second apical portion 8 has a conical cylindrical or conical shape convergent towards said apical end E _a .

• l'implant 1 selon l'invention ; et
• un élément transgingival 9 agencé pour être relié à la portion coronaire 3 du corps d'ancrage 2 et destiné à supporter un élément prothétique.

The figures 2 and 3 illustrate two different embodiments of the prosthetic assembly comprising:

• the implant 1 according to the invention; and
• a transgingival element 9 arranged to be connected to the coronal portion 3 of the anchoring body 2 and for supporting a prosthetic element.

The transgingival element 9 has a third length L ₃ equal to a thickness of gingiva 9 '"of the implantation site In general, this third length L ₃ is between 3.00 mm and 4.00 mm.

In a first embodiment of the assembly according to the invention ( figure 2 ), the set is a set of type " Tissue Level " and comprises a transgingival element 9 present in the form of a neck 9 'projecting in the extension of the first coronal portion 3 of the anchoring body 2, along the longitudinal axis a _L , in a direction opposite to the _E apical end of the anchor body 2. in this way, the prosthesis neck 9 and the anchor body 2 form a single body.

In a second embodiment of the assembly according to the invention ( Figures 3a to 3c ), the assembly is a set of " Bone Level " type where the transgingival element 9 is a pillar 9 "connected, preferably removably, by a first connecting means 10 to the coronal portion 3 of the anchoring body 2.

The first connection means 10 which connects the pillar 9 "to the coronal portion 3 of the anchoring body 2 comprises a head body 10a projecting from the cervical end E _c of the anchoring body 2 along said longitudinal axis a _L , and having a bevel base cut obliquely to a horizontal plane passing through the cervical end E _c of the anchoring body 2. The head body 10a protrudes in a direction opposite to said apical end E _a of the anchoring body 3. The head body 10a is further arranged to fit into a first cavity 10b present in the pillar 9 "through a cavity opening 10c of the pillar ( figure 3a ).

Preferably, the head body 10a has a conical shape and the first cavity 10b of the pillar is of complementary shape to that of the head body 10a. Preferably, the taper of the head body 10a is greater than 0%, preferably between 0.10% and 10%.

• , où d correspond au diamètre d'extrémité basale du cône ;
• D' correspond au diamètre d'extrémité cervicale du cône ; et
• H correspond à la hauteur du cône.

The conicity C of a cone is defined in the context of the present invention as follows: $$\boxed{\mathrm{C}\left(\mathrm{in}\%\right)=\left[\left(d-\mathrm{D}\text{'}\right)/\mathrm{H}\right]\times 100}$$

• where d is the basal end diameter of the cone;
• D 'corresponds to the cervical end diameter of the cone; and
• H corresponds to the height of the cone.

Preferably, the head body 10a further comprises a second threaded cavity 10d arranged to receive a screw 10e, having a screw body and a screw head, through an opening 10f of the head body cavity 10d 10a. The pillar 9 "has an orifice 10g giving access to the cavity 10d of the head body 10a, so that the pillar 9" can be connected resting on the head body 10a by the screw head 10e which, once screwed into the second cavity 10d of the head body 10a compresses an apical surface portion of the pillar 9 "on the head body ( Figures 3b and 3c ).

Alternatively (not shown), the pillar 9 "is provided on its base with an apical element protruding from the base and arranged to be housed in a cavity formed in the coronal portion of the implant, through a defined opening on the cervical end of the implant.

The figure 4 illustrates a third embodiment of the prosthetic assembly according to a truncated view.

In this embodiment, the coronal portion 3 of the implant is defined by a lateral wall 11 having a first vestibular surface 11a and a second palatal face 11b, which palatal face 11b is in a position offset to the cervical end E _c relative to that of the vestibular face 11a along the longitudinal axis a _L.

The palatal face is the face that is intended to be oriented towards the palate of the oral cavity after implant placement.

The vestibular surface is the opposite side to the palatal face.

In addition, in this type of implant, the concavity of the coronal portion is double slope.

In addition, as illustrated by figure 4 advantageously, the head body 10a has at least one part characterized by a substantially polygonal cross-section (square 10 ', pentagonal 10 ", hexagonal 10"'), the cavity 10b of the pillar being of polygonal shape complementary to that of the head body 10a. As shown in this figure, the cross-sections are scalloped polygonal cross-sections that have rounded edges that take the form of bevels.

For all the embodiments described above, an osteo-stimulating material may be deposited on the surface of the anchoring body, in particular on the surface of the coronal portion of the implant, so as to stimulate the bone recovery once the implant placed on the implantation site. In this context, the space created between the crests of the turns of the net constitute reservoirs of the osteo-stimulant material.

Comparisons by Modeling of a Classical Dental Implant of the State of the Art with a Dental Implant According to the Invention

Finite element modeling (using Samcef software version 16 from SAMTECH) was carried out on three-dimensional implant models (made with CREO version 2 software from PTC) in order to compare mechanically a conventional dental implant of the state of the art and an implant according to the invention, these two implants being formed of Ti6AL4V titanium alloy (with a Young's modulus set at 110 GPa for the calculation).

These modelizations were carried out in order to determine and compare (1) the global contact surfaces of the dental implant with the dense bone and the cancellous bone, (2) the compressive stresses exerted on the one hand in the bone and on the other hand in the cancellous bone and (3) the compressive stresses exerted within the dental implant itself when a predetermined force is applied along the longitudinal axis (a _L ) of the dental implant at its cervical end (E _C ).

The force considered and applied in the context of these finite element modelizations was fixed at 150 N, which corresponds to a medium molar chewing force ( Guillaume Odin. Numerical modeling of the mandibular bone applied to dental and maxillofacial implantology. Modeling and Simulation. National School of Mines of Paris, 2008 ).

The characteristics of each of these dental implants are shown in Table 1 below: Table 1: Classical dental implant of the state of the art Dental implant according to the invention Length (L1) 8.7 mm 8.7 mm Nominal diameter (d _n ) 4.27 mm 4.27 mm External diameter (d _e ) 4 mm 2 mm D ratio _n / d _e 1,067 2,135

Moreover, in order to carry out these finite element modelizations, the following values of Young's modulus (modulus of elasticity) have been fixed for the different elements to be taken into account. These values are shown in Table 2 below: Table 2: Young's module (MPa) Dense bone 3000 * Cancellous bone 300 * Dental implant 110.000 * Guillaume Odin. Numerical modeling of the mandibular bone applied to dental and maxillofacial implantology. Modeling and Simulation. National School of Mines of Paris, 2008 .

The results obtained are shown in Table 3 below: Table 3: Classical dental implant of the state of the art Dental implant according to the invention Overall contact area (with dense bone and cancellous bone) 132.3 mm ² 150.3 mm ² Compression stress in dense bone 83.1 MPa 100.9 MPa Compression stress exerted in the cancellous bone 6.7 MPa 7.1 MPa Compression stress exerted in the dental implant 7.7 MPa 8.5 MPa

As can be seen, the overall contact area of the dental implant according to the invention with the dense bone and cancellous bone is increased. Moreover, the compressive stresses respectively exerted in the dense bone, in the cancellous bone and in the implant are also increased for an implant according to the invention whose ratio d _n / d _e is between 2 and 4 ( ratio d _n / d _e = 2.135 according to the implant according to the invention considered in the finite element modeling).

Increases in compressing dense and spongy bone by means of a dental implant according to the invention are particularly advantageous since they make it possible to stimulate the bone tissue so that they reform faster and all the better around the dental implant.

It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made without departing from the scope of the appended claims.

Claims (8)

1. Dental implant (1) formed of an anchoring body anchoring body (2) defined between an apical end (E_a) and a cervical end (E_c), which anchoring body (2) is a body of first predetermined length L₁ and has on the outer surface thereof and along the whole of said first predetermined length at least one thread (4), said anchoring body (2) comprising on at least one coronal portion (3) of the implant (1), a part of said at least one thread (4) having a nominal diameter d_n, which implant is characterised in that said nominal diameter d_n is greater than an outer diameter d_e of said anchoring body (2) on said coronal portion (3) in a first d_n/d_e ratio between 2.00 and 4.00, preferably between 2.00 and 3.00.
2. Dental implant according to claim 1, wherein said anchoring body is at least in part, of substantially cylindrical shape.
3. Dental implant according to claim 1 or 2, wherein said anchoring body has a conico-cylindrical or conical shape and features a conicity converging towards said apical end (E_a).
4. Dental implant according to any one of the preceding claims, wherein said coronal portion (3) is defined by a side wall (11) which has a first vestibular face (11a) and a second palatine face (11b), which palatine face (11b) is in an offset position towards said cervical end (E_c) with respect to that of the vestibular face (11a) along a longitudinal axis (a_L) intersecting the anchoring body (2) and connecting said first cervical end (E_c) to said apical end (E_a).
5. Dental implant according to any one of the preceding claims, wherein said anchoring body (2) has, at the apical end (E_a) thereof, at least one threading notch (6) constituted of at least one longitudinal recess, preferably arranged from the apical end (E_a) towards the cervical end (E_c) of the anchoring body (3).
6. Prosthetic unit comprising:

   - said implant according to any one of claims 1 to 5; and

   - a transgingival element (9) arranged to be connected to the coronal portion (3) of the anchoring body (2) and intended to support a prosthetic element.
7. Prosthetic unit according to claim 6, wherein said transgingival element is a collar (9') protruding from the cervical end (E_c) of the implant which is arranged in the extension of the coronal portion (3) of the anchoring body (2).
8. Prosthetic unit according to claim 6, wherein the transgingival element is a column (9") connected, preferably so that it can be removed, by a means for connecting (10) to said coronal portion (3) of the anchoring body (2).

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